ArcGIS Server Web ADF缓冲区分析的开发

ArcGIS Server Web ADF开发不提供缓冲区分析的算法，但是ArcObject中提供了缓冲区相关接口ITopologicalOperator的Buffer方法。所以可以用ArcGIS Server远程调用ArcObject缓冲区分析功能。但是调用缓冲区分析功能后的，ADF需要实现缓冲区的表现，通常是采用通过Graphics Layer来实现。ADF通过MapResourceManage添加数据源的时候除了可以添加ArcGIS Server、ArcIMS、OGC等地图数据源外，还支持Graphics 数据源。ADF(或者说MapResourceManager)中的Graphics数据源可以支持两种图层，分别ElementGraphicsLayer 和 FeatureGraphicsLayer，两者都是System.Data.DataTable类型。用以下语句来添加要素图层Graphics数据源中：

gResource.Graphics.Tables.Add(elementgraphicglayer);

        ElementGraphicsLayer一般用来显示基本的图形元素，一个ElementGraphicsLayer可以同时存放不同几何类型（点、线、面等）的元素。一个典型的应用为用该图层来显示被选择的要素（Feature）。
        FeatureGraphicsLayer用来模拟要素图层并且存储要素的属性信息。所以可以在客户端根据属性来渲染不同的要素。一个FeatureGraphicsLayer图层只能存放一种几何类型的元素。FeatureGraphicsLayer也支持查询。
       Graphic图层中的元素都被存储在内存中，这点与服务器层的Graphic图层不同，后者将元素直接输出到图片上（可以在OutPut文件下查看）。
此外，MapResourceManager只能添加空的Graphics数据源，图层（GraphicsLayer）及元素（Graphic Element）的操作都必须通过编程实现。

       因此，首先要在VS中创建两个资源连接，一个是连接地图服务（ArcGIS Server Local），另一个是内存图像（GraphicsLayer），如下图，用来画缓冲图形。

 

然后添加MapResourceManager和Map控件，用代码添加文本框和缓冲区分析按钮如下：

<table>
   <tr>
   <td>请输入城市名称</td>
   <td><input id ="TxtName" type ="text" /></td>
   <td><input id ="OkBut"  type ="button" value="缓冲分析" onclick ="GetAttriValue()"/>
       </td>
   </tr>
   </table>

 下一步编写客户端向服务器传递消息，促使服务发生异步调用的Javascript函数，代码如下：

<script language ="javascript" type="text/javascript">
        function GetAttriValue()
        {
            var name = document.getElementById("TxtName").value;
            if(name=='')
            {
                alert('请输入城市名称');
                document.getElementById("TxtName").focus();
                return;
            }
        var message = name;    //传递消息
        var context = 'Map1';
        <%=m_ADFCallbackFunctionString%> //调用异步处理

        }
    </script>

下面是服务器端的相应源码：

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.ADF;

namespace BufferAanalyze
{
    public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
    {
        public string m_ADFCallbackFunctionString;
        protected void Page_Load(object sender, EventArgs e)
        {
            m_ADFCallbackFunctionString = Page.ClientScript.GetCallbackEventReference(this, "message",
           "processCallbackResult", "context", "postBackError", true);
        }

        public void RaiseCallbackEvent(string eventargs)
        {
            System.Collections.IEnumerable func_enum = null;
            //获取当前map1控件中所有的functionality
            func_enum = Map1.GetFunctionalities();

            System.Data.DataTable datatable;
            //对所有的functionality进行遍历
            foreach (ESRI.ArcGIS.ADF.Web.DataSources.IGISFunctionality gisfunctionality in func_enum)
            {
                ESRI.ArcGIS.ADF.Web.DataSources.IGISResource gisresource = null;
                //得到该functionality的resource
                gisresource = gisfunctionality.Resource;
                //判断该resource是否支持IQueryFunctionality
                bool supported = false;
                supported = gisresource.SupportsFunctionality(typeof(ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality));
                if (supported)
                {
                    ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality qfunc;
                    qfunc = (ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality)gisresource.CreateFunctionality(typeof(ESRI.ArcGIS.ADF.Web.DataSources.IQueryFunctionality), null);

                    string[] lids;
                    string[] lnames;
                    //获得图层的layerId和layerName，GetQueryableLayers的重载方法可以指定图层类型
                    qfunc.GetQueryableLayers(null, out lids, out lnames);

                    int selindex = -1;
                    for (int i = 0; i < lids.Length; i++)
                    {
                        if (lnames[i] == "行政区划")
                        {
                            //找到行政区划图层的序号
                            selindex = i;
                            break;
                        }
                    }

                    if (selindex > -1)
                    {
                        //设置过滤器的过滤条件
                        ESRI.ArcGIS.ADF.Web.SpatialFilter spatialfilter = new ESRI.ArcGIS.ADF.Web.SpatialFilter();
                        spatialfilter.ReturnADFGeometries = true;
                        spatialfilter.MaxRecords = 100;
                        spatialfilter.WhereClause = "名称  like '%" + eventargs + "%'";

                        //对指定的图层进行查询，查询的结果保存为
                        datatable = qfunc.Query(null, lids[selindex], spatialfilter);
                        if (datatable != null)
                        {
                            if (datatable.Rows.Count > 0)
                            {
                                for (int j = 0; j < datatable.Columns.Count; j++)
                                {
                                    if (datatable.Columns[j].DataType == typeof(ESRI.ArcGIS.ADF.Web.Geometry.Geometry))
                                    {
                                       //找到该点
                                        ESRI.ArcGIS.ADF.Web.Geometry.Geometry pnt = (ESRI.ArcGIS.ADF.Web.Geometry.Geometry)datatable.Rows[0][j];

                                       //对该点进行缓冲分析
                                        //1,连接服务器
                                        ESRI.ArcGIS.ADF.Connection.AGS.AGSServerConnection connection = new ESRI.ArcGIS.ADF.Connection.AGS.AGSServerConnection();
                                        connection.Host = "localhost";
                                        connection.Connect();

                                        //2获得服务器对象
                                        ESRI.ArcGIS.Server.IServerObjectManager pSOM = connection.ServerObjectManager;
                                        ESRI.ArcGIS.Server.IServerContext pSC = pSOM.CreateServerContext("地图", "MapServer");//服务名和类型
                                        ESRI.ArcGIS.Carto.IMapServer mapserver = pSC.ServerObject as ESRI.ArcGIS.Carto.IMapServer;

                                        //3使用服务器对象
                                        ESRI.ArcGIS.Carto.IMapServerObjects pMSO = (ESRI.ArcGIS.Carto.IMapServerObjects)mapserver;
                                        ESRI.ArcGIS.Geometry.IGeometry compnt = (ESRI.ArcGIS.Geometry.IGeometry)ESRI.ArcGIS.ADF.Web.DataSources.ArcGISServer.Converter.ToIGeometry(pnt, pSC);//ValueObjectToComObject(pnt, pSC);
                                        ESRI.ArcGIS.Geometry.SpatialReferenceEnvironment sre = new ESRI.ArcGIS.Geometry.SpatialReferenceEnvironment();

                                        ESRI.ArcGIS.Geometry.ISpatialReference pSR = sre.CreateGeographicCoordinateSystem(4326);
                                        compnt.SpatialReference = pSR;
                                        ESRI.ArcGIS.Geometry.ITopologicalOperator pTOPO = (ESRI.ArcGIS.Geometry.ITopologicalOperator)compnt;

                                        pTOPO.Simplify();
                                        double bufdis = Map1.Extent.Width / 2;
                                        ESRI.ArcGIS.Geometry.IPolygon bufPoly = (ESRI.ArcGIS.Geometry.IPolygon)pTOPO.Buffer(1);
                                        ESRI.ArcGIS.ADF.ArcGISServer.PolygonN valuePoly = (ESRI.ArcGIS.ADF.ArcGISServer.PolygonN)ESRI.ArcGIS.ADF.Web.DataSources.ArcGISServer.Converter.ComObjectToValueObject(bufPoly, pSC, typeof(ESRI.ArcGIS.ADF.ArcGISServer.PolygonN));
                                        ESRI.ArcGIS.ADF.Web.Geometry.Polygon adfpoly = (ESRI.ArcGIS.ADF.Web.Geometry.Polygon)ESRI.ArcGIS.ADF.Web.DataSources.ArcGISServer.Converter.ToAdfPolygon(valuePoly);


                                        ESRI.ArcGIS.ADF.Web.Geometry.Geometry geom = adfpoly;
                                        ESRI.ArcGIS.ADF.Web.Display.Graphics.GraphicElement ge = new ESRI.ArcGIS.ADF.Web.Display.Graphics.GraphicElement(geom, System.Drawing.Color.BlueViolet);
                                        Map1.Zoom(adfpoly);

                                        ge.Symbol.Transparency = 70;

                                        System.Collections.IEnumerable gfc = Map1.GetFunctionalities();
                                        ESRI.ArcGIS.ADF.Web.DataSources.Graphics.MapResource gmap = null;

                                        foreach (ESRI.ArcGIS.ADF.Web.DataSources.IGISFunctionality gfunc in gfc)
                                        {
                                            if (gfunc.Resource.Name == "graph")
                                            {
                                                gmap = (ESRI.ArcGIS.ADF.Web.DataSources.Graphics.MapResource)gfunc.Resource;
                                            }
                                        }

                                        if (gmap == null) return;
                                        ESRI.ArcGIS.ADF.Web.Display.Graphics.ElementGraphicsLayer glayer = null;
                                        foreach (System.Data.DataTable dt in gmap.Graphics.Tables)
                                        {
                                            if (dt is ESRI.ArcGIS.ADF.Web.Display.Graphics.ElementGraphicsLayer)
                                            {
                                                glayer = (ESRI.ArcGIS.ADF.Web.Display.Graphics.ElementGraphicsLayer)dt;
                                                break;
                                            }
                                        }

                                        if (glayer == null)
                                        {
                                            glayer = new ESRI.ArcGIS.ADF.Web.Display.Graphics.ElementGraphicsLayer();
                                            gmap.Graphics.Tables.Add(glayer);
                                        }

                                        glayer.Clear();//清除以后数据
                                        glayer.Add(ge);

                                        //4释放服务器对象
                                        pSC.ReleaseContext();

                                        if (Map1.ImageBlendingMode == ESRI.ArcGIS.ADF.Web.UI.WebControls.ImageBlendingMode.WebTier)
                                            Map1.Refresh();
                                        else if (Map1.ImageBlendingMode == ESRI.ArcGIS.ADF.Web.UI.WebControls.ImageBlendingMode.Browser)
                                            Map1.RefreshResource(gmap.Name);


                                        m_ADFCallbackFunctionString = Map1.CallbackResults.ToString();
                                        return;
                                    }
                                }
                            }
                            else
                            {
                                object[] ob = new object[1];
                                string sa = "alert('没有找到该城市');";
                                ob[0] = sa;
                                ESRI.ArcGIS.ADF.Web.UI.WebControls.CallbackResult callbackresult = new ESRI.ArcGIS.ADF.Web.UI.WebControls.CallbackResult(null, null, "JavaScript", ob);
                                Map1.CallbackResults.Add(callbackresult);
                                m_ADFCallbackFunctionString = Map1.CallbackResults.ToString();

                            }
                        }
                    }
                }
            }

        }

        public string GetCallbackResult()
        {
            return m_ADFCallbackFunctionString;
        }


    }
}

运行结果如下图：